a) Field of the Invention
The invention is directed to a process and an arrangement for producing dose profiles for the fabrication of structured surfaces with a beam which is used for exposure and is directed on the surface.
b) Description of the Related Art
Devices and processes employing the technique of variable dose writing to fabricate surface profiles for electron-beam lithography and photolithography are known (T. Fujita, H. Nishihara, J. Kayama, "Blazed grating and Fresnel lenses fabricated by electron-beam lithography", Opt. Lett. 7 (1982) 12, p. 578; M. Haruna, M. Takahishi, K. Wakahayhashi, H. Nishihara, "Laser beam lithographed Micro-Fresnel lenses", Applied Optics/Vol. 29, No. 34/1 December 1990).
The fact that the dissolve rate of a radiation-sensitive resist in the developer bath can be predetermined by the radiation dose introduced in the resist is made use of. Accordingly, it is possible to design the lateral radiation dose distribution in such a way that the desired surface profile is obtained after a certain period of time following development. FIG. 14 illustrates this procedure schematically.
However, the high cost of the facilities for producing the dose profiles required for this process poses problems, since the systems which have been used up to now, such as electron-beam writing devices or laser pattern generators, are physically large and very expensive. Further, very long processing times are necessary for extended surface profiles. The fabrication of micro-lenses and micro-lens arrays especially is highly time-consuming. Further, the amounts of data needed to write the required dose profiles are sometimes enormous, requiring a corresponding expenditure on computer technology.